This invention relates to telephone call timing systems and more particularly to electronic devices for providing an indication of the total elapsed time of a telephone call, a cumulative total indicating length of use of a telephone over a predetermined interval (e.g. a day, a week, a month), or both.
Devices are known which are employed to measure the length of time of an individual phone call from a given telephone, the acumulated usage on a time basis of the telephone, and a combination of both. U.S. Pat. No. 3,512,335, for example, discloses an electromechanical device having a pair of clock displays for timing the length of an individual phone call and for accumulating the total length of telephone usage over a fourteen-day interval. While devices of this type may be useful, they are primarily mechanical in nature and thus require a relatively large number of mechanical components which are prone to ordinary wear and ultimate failure. In addition, such devices employing mechanical components are relatively large in size and somewhat cumbersome, so as to be unsuitable for use in those applications where space is at a premium. Further, such devices rely upon mechanical cooperation with the telephone receiver for proper actuation and thus must be physically designed to be mechanically cooperable with a telephone handset of a particular design. Accordingly, several different models of such devices are required, each mechanically conformable with a different type of telephone handset, e.g. the conventional desk handset, the wall hanging model, and other models such as the PRINCESS telephone, special console models, and the like.